#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N = 1000;
const int M = 1e9+7;

unordered_set<string> s;
int n;


int main()
{
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    ios::sync_with_stdio(false), cin.tie(0);
    cin >> n;
    for(int i = 0; i < n; i++) {
        string a, b;
        cin >> a >> b;

        s.insert(a + " " + b);
    }    

    if (s.size() == n) puts("No");
    else puts("Yes");
    return 0;
}